Heat has a natural tendancy to rise, so work with that dynamic and allow the fans to push air up through the rad and out of the case- it will result in an overall cooler system. The air might be a tiny bit warmer that you're sending up through the rad when taking air from in the case, but the flow will be improved when working with the heat gradient, and warm air won't be concentrated in the case and warming up other components.

ahh i c... since i will be using a dual rad, what if i let the air blow into the case and put another 120mm case on the last slot at the top of the case? (closest to the top mount psu?) or that fan wouldnt have any bit effect? lol